When controlling a machine tool by an NC device based on a processing program so as to process a workpiece which is fastened to a table, sometimes a situation ends up arising where the position instructed to the linear feed axis or rotational feed axis of the machine tool ends up outside of the actual movable range of the feed axis (called “stroke-over”). To deal with such stroke-over, in the past, there has been known a system which, when a table rotation command which would result in stroke-over at the linear feed axis is output during path control of the front end point of the tool, maintains the distance between the front end point of the tool and the center of the table rotation constant from the start of table rotation to the end of table rotation while making the tool retract to thereby try to avoid the stroke-over (for example, see PLT 1).
However, with a system such as described in PLT 1 where the tool is made to retract to try to avoid stroke-over, it is difficult to smoothly process the entire area of the workpiece based on a processing program.
PLT 1: International Publication No. 2011/111088A